Neural Circuitry of Fear and Anxiety

Section through a part of the mouse brain involved in stress and anxiety, imaged to visualize expression of corticotrophin releasing hormone receptor type 2 (green), channelrhodopsin2 (blue) and the immediate early gene fosB (red).Credit: Credit: Todd Anthony

Fear is a highly conserved emotion with specific behavioral expressions. A great deal has been learned about the brain structures involved in processing learned (conditioned) fear, such as the anatomic subdivisions of the amygdala, but much less is known about the neuronal microcircuits that control fear within those brain structures. Using molecular markers for specific neuronal subtypes, and optogenetic and pharmacogenetic manipulations of neuronal activity as well as virally based tools for mapping neural connectivity, we are elucidating the structure and function of brain microcircuits that control fear. We are carrying out such investigations in both the amygdala, and in other, less explored areas such as the lateral septum. We are interested in how circuits for learned fear are related to those that control innate fear, as well to those that control anxiety. An elucidation of neural circuits for fear and anxiety should provide a cellular platform for understanding how genes, drugs and experience act on and modify these circuits, in both normal behavior and in affective disorders such as anxiety and depression, and may lead to the identification of novel candidate drug targets for these disorders.